Rotatable power tools, such as electric drills, are often used in situations where the rotatable accessory may come into contact with a source of electricity. For example, the drill bit of a power drill may sever a wire located within a wall, or the drill may even cut into its own cord. Accordingly, for the safety of the tool operator, it is important to prevent the electric current from reaching the operator.
One known method of preventing electric current from reaching the operator includes the use of an insulating housing with insulated hand grip areas. Another known method, which is described in U.S. Pat. No. 3,685,843 to Anthony Jacyno, involves the use of an insulating member that is positioned within a metal drill chuck, for preventing flow of electric current between the drill chuck and the rotating spindle. A similar type of insulating sleeve is also described in U.S. Pat. No. 3,797,960 to Donald J. McCarthy.
One problem with these known insulating methods is that there is still a danger of electric shock if the operator's hand or other body part contacts the chuck assembly while the rotatable accessory is in contact with the electrical wire. While these prior art insulating methods do insulate between the drill bit and the handle of the device, they usually fail to insulate between the drill bit and the chuck assembly (which holds the drill bit in position). Thus, the electric current is free to flow from the drill bit, to the chuck assembly, and then to the operator if, for example, the operator's hand makes contact with the chuck assembly, which is normally made of metal.
Accordingly, it is an object of the present invention to provide an improved rotatable power tool which provides insulated components therein for preventing electric current from being transferred from the rotatable accessory to the operator.
Another object of the present invention is to provide an improved chuck assembly which is insulated in such a manner that prevents electric current from being transferred from a rotatable accessory to the outer surface of the chuck assembly.
An additional object of the present invention is to provide an improved insulated chuck assembly that is inexpensive and can be utilized with existing chuck assembly configurations.
Yet another object of the present invention is to provide an insulating chuck jaw that can be used, in combination with other similar chuck jaws, in a chuck jaw assembly for providing superior electrical insulation therein.